introducing the new structural response prediction...

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Curt B. Haselton, PhD, PE (and Jack Baker and the SP3 Team)

Professor of Civil Engineering @ CSU, Chico

Co-Founder and CEO @ Seismic Performance Prediction Program (SP3)

www.hbrisk.com

SP3 Software Webinar Series

Introducing the New Structural Response

Prediction Engine

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All phone lines are muted Questions are highly encourage (answered at end) Handouts are available – presentation slides and one-page

summary of the new method Webinar is recorded and video will be distributed Please take a brief survey before signing off at end of webinar

Housekeeping

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Questions:• Please use questions tab

and we will address as many as we can at the end.

• For further questions, contact Dr. Haselton directly ([email protected]) or contact the SP3 team ([email protected]).

Housekeeping

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This is the first webinar in our series, so please watch for announcements for our next three webinars!

Webinar Series:1) The new SP3 Structural Response Prediction Engine2) Risk assessment of wood light-frame buildings using SP33) Risk assessment of tilt-up buildings using SP34) SP3: A consistent platform for building-specific seismic risk

assessment for low-levels to high-levels of building input information

Housekeeping

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Curt B. Haselton, PhD, PE (and Jack Baker and the SP3 Team)

Professor of Civil Engineering @ CSU, Chico

Co-Founder and CEO @ Seismic Performance Prediction Program (SP3)

www.hbrisk.com

SP3 Software Webinar Series

Introducing the New Structural Response

Prediction Engine

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Brief overview of FEMA P-58 and the SP3 software The need for rapid and advanced seismic risk evaluation The new Structural Response Prediction Engine:

• Overview of approach• Detail of what is under the hood• What the Engine now enables

Current and next steps for SP3 Research & Development Questions

Outline for Today

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FEMA P-58 is a probabilistic performance prediction methodology (15 years of effort to date, ~$16M invested by FEMA)

FEMA P-58 is tailored for building-specific analysis (in contrast to most risk assessment methods that give results by building class)

FEMA P-58 output results:• Repair costs• Repair time• Safety: Fatalities & injuries

FEMA P-58 Overview

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FEMA P-58 Overview

Ground Motion Hazard

Component DamageEconomic Loss

Casualties

Repair Time

Structural Responses

SP3 uses FEMA P-58 and adds much more:

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FEMA P-58 provides the comprehensive and standardized

building-specific risk assessment (with ~$16M to develop).

SP3 provides a user-friendly software to integrate all steps in a FEMA P-58

risk assessment.

The initial assessment should take a couple hours and not days or

weeks.

SP3 Software Compliments FEMA P-58

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Our Goal: To enable and facilitate rapid and advanced building-specific seismic risk assessments for all buildings(i.e. building-specific vulnerability curves).

Expected Outcomes: We believe that this will (a) facilitate the design of moreresilient buildings and (b) enable better risk-relateddecision making (e.g. insurance risk, mortgage risk, etc.).

Our Goal with SP3

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Current uses of SP3:• Licensed by ~80+% of the large west-coast structural engineering firms, and

has been expanding from there.

• Currently being used for:

• Resilient design of new buildings (municipal buildings, court houses, etc.)

• Retrofit of existing buildings

• Assessments of special facilities (EOCs, manufacturing, museums, etc.)

• Mortgage risk assessments [needs rapid risk methods]

• Investment risk assessments [needs rapid risk methods]

• Insurance risk assessments [needs rapid risk methods]

Current Uses of SP3 Software

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Our Goal with SP3

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Our Goal with SP3

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Ground Motion Hazard

Component DamageEconomic Loss

Casualties

Repair Time


The Need for Rapid Risk Evaluations

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SP3 Structural Response Prediction ENGINE

“We do the nonlinear dynamic structural analysis for you.”

The Need for Rapid Risk Evaluations

[and contrast to FEMA P-58 “Simplified Method”]

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Outline for Today

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Outline for Today

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We first assembled a large set of structural models and simulated nonlinear responses for many ground motion levels.

Approach to the SP3 Str. Response Prediction Engine

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0.2

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0.3

0.4

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0.5

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0.6

IDR

Cor

rela

tion

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0.7

10

0.8

Story Number

6 8

0.9

Story Number

6

1

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0 0

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Engineering Demand Parameters for ~100 ground motions

(drifts and floor accelerations)

SP3 Structural Response Prediction ENGINE“We do the nonlinear dynamic structural analysis for you.”


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SP3 Structural Response Prediction ENGINE

“We do the nonlinear dynamic structural analysis for you.”

SP3 Auto-Population ENGINE

Structural Inputs:- Building strength

- T1, T2, and T3

- First three mode shapes

Inputs:- Building system and height- Building age (and/or code)

- Building location- Other optional site/design info.

Database: Structural responses from hundreds of nonlinear structural models with millions of nonlinear response-history analyses.


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Inputs for New “Low Data” Option:- Building system and height- Building age (and/or code)

- Building location- Other optional site/design info.


Previous “Full Data” Option:

- Create a structural model, run nonlinear response-history analyses, and input results

manually.

Inputs for New “Intermediate Data” Option:

- Building strength- T1, T2, and T3

- First three mode shapes

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This was an overview of how we created the new SP3 Response Engine. Let’s now get into more of the detail.

Creating the SP3 Str. Response Prediction Engine

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Example data set for a 12-story Reinforced Concrete Special Moment Frame in high-seismic California.


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Creating the drift prediction algorithm:

Step 1: Use nonlinear response data set to get correct building global displacement demands.

• Start with ASCE 41 target displacement.• Correct this based on the database of structural responses.


𝛿𝛿𝑡𝑡 = 𝐶𝐶0𝐶𝐶1 𝐶𝐶2𝑆𝑆𝑎𝑎𝑇𝑇𝑒𝑒2

4𝜋𝜋2 𝑔𝑔

0 1 2 3 4 5 6

S (Sa(Teff)/Vmax)

0

0.005

0.01

0.015

RD

R

Observered RDR 1015

Predicted RDR 1015

ASCE41 RDR 1015

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Step 2: Since peak story drifts over height do not occur all at the same time, use the database data to get the average story drifts correct.


0 1 2 3 4 5 6

S (Sa(T1)/Vmax

0

0.005

0.01

0.015

Ave

rage

IDR

Observed ave IDR: model 1015

Predicted ave IDR: model 1015

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0 0.005 0.01 0.015 0.02 0.025 0.03

IDR

0

2

4

6

8

10

12

Sto

ry

Opensees IDR: S = 0.80Elastic IDR: S = 0.80






Step 3: Do a three-mode modal analysis to compute elastic story drift profiles. This is based on T1-T3 and φ1-φ3 either from an input or auto-populated based on building type and design information.


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Step 4: Use the response database to modify the response to account for inelastic effects.

• This includes an adjustment to the global drifts, to account for inelastic damping effects (when they occur).

• This also handles where the drifts localize over height (which depend on structural system and design approach, e.g. strong column-weak beam).


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0 0.005 0.01 0.015 0.02 0.025 0.03

IDR

0

2

4

6

8

10

12

Sto

ry


Predicted IDR: S = 0.80










Step 4: Use the response database to modify the response to account for inelastic effects.


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The drift prediction algorithm is now done! Now, let’s look at creating the floor acceleration prediction

algorithm.


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0 0.5 1 1.5

Acceleration (g)

0

2

4

6

8

10

12

Floo

r

Opensees PFA: S = 0.80

Opensees PFA: S = 1.82Elastic PFA: S = 1.82




Creating the floor acceleration prediction algorithm:

Step 1: Do a three-mode modal analysis to estimate elastic floor accelerations.


𝑃𝑃𝑃𝑃𝑃𝑃𝑛𝑛 = �𝑖𝑖=1

3

Γ𝑖𝑖𝜙𝜙𝑖𝑖,𝑛𝑛�̈�𝑢(𝑡𝑡)𝑖𝑖

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0 0.5 1 1.5

Acceleration (g)

0

2

4

6

8

10

12

Floo

r

Opensees PFA: S = 0.80Predicted PFA: S = 0.80

Elastic PFA: S = 0.80









Creating the floor acceleration prediction algorithm:

Step 2: Use structural response database to capture the effects of inelastic behavior.


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Response correlations:• Getting these right is crucial to getting a meaningful estimate of

variability in the final risk prediction (e.g. getting full curve to estimate things like 90th percentile of losses).


0.2

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0.3

0.4

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0.5

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IDR

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0.7

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Story Number

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This new ENGINE enables a high-fidelity SP3 risk assessment without

needing to build a nonlinear structural model.

This does not replace modeling by a structural engineer and

some applications of SP3 will still include modeling, in order to reduce the uncertainty in the risk

assessment (e.g. for resilient design of new buildings).

However, this opens the door to high-fidelity risk assessments for the

many cases where a structural model is not feasible (e.g. initial structural design, insurance risk,

mortgage risk, investment risk, etc.).

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Current scoping limitations of SP3 Structural Response Prediction Engine:

• Applies up to 25 stories (wood up to 5-story with up to 2-story pedestal)• Calibrated for both ductile and non-ductile buildings

(e.g. RC SMF, OMF, and 1960’s RC frames)• Regular buildings (and currently being extended)• Data set supports low levels of ground motion (elastic) to high levels

(highly nonlinear); include response up to 25% collapse rate (so no meaningful limits on ductility level)

• Response correlations are carefully tracked, so a full distribution of risk results can be reliably provided (e.g. 90% percentile).

• Most aspects of the Engine are generic to all structural systems (e.g. modal analysis), but inelastic factors are currently based on frame data (and are currently being extended).


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With substantial funding from the National Science Foundation ($980k to date), we are also continuing further development for rapid and advanced building-specific risk assessment.

The research focuses are:

Further extending and refining the Structural Response Prediction Engine.

Rapid assessment of wood light-frame buildings (done).

Rapid assessment of tilt-up buildings.

Next Research and Development Steps

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Next steps on the SP3 Response Engine:• Extend to taller – up to 40 stories• Refine inelastic factors for additional structural systems – e.g.

current in-progress project looking at buckling-restrained braced frame buildings up to 40-stories

• Extend to irregular – vertical weak story and plan torsion (structural analyses are already completed in the database)


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Wood light frame (covers single- and multi-family, up to 5-stories of wood and 1-2 stories of podium) [method is complete]


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Tilt-up buildings (rigid-wall flexible diaphragm) – inclusive of all building era’s, focus on tilt-up panels with wood diaphragms (i.e. buildings is western half of the U.S.)


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Closing and Questions

Thank you for your time. Our goal is to support adoption of resilience-based design and risk

assessment, and we welcome feedback and suggestions.

Time for questions!

Curt Haselton: [email protected], Direct: (530) 514-8980

Jack Baker: [email protected]

www.hbrisk.com

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Please watch for announcements for our next three webinars!

Webinar Series:1) The new SP3 Structural Response Prediction Engine2) Risk assessment of wood light-frame buildings using SP33) Risk assessment of tilt-up buildings using SP34) SP3: A consistent platform for building-specific seismic risk

assessment for any levels of building information

Upcoming Webinars in this Series

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© HB Risk Group

Questions:• Please use questions tab

and we will address as many as we can at the end.

• For further questions, contact Dr. Haselton directly ([email protected]) or contact the SP3 team ([email protected]).

Closing and Questions

introducing the new structural response prediction...

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